What does this mean? Xft can be initialized from X Resource?

[It's me FKtPp ;)]

Dear developers:

I configured  my XEmacs use the following XFT face-font:

--8<---------------cut here---------------start------------->8---
(define-specifier-tag 'lang-cn)
(set-face-font 'default "Bitstream Vera Sans Mono-15")
(set-face-font 'default "SimSun-15"
;              nil '(lang-cn) 'remove-tag-set-append)
               nil '(lang-cn) 'append)
--8<---------------cut here---------------end--------------->8---

But XEmacs always warning me as follow when it started. Does X
Resource have anything todo with XFT font configuration? Is there
anything I can do to get rid of this?

--8<---------------cut here---------------start------------->8---
(1) (font/warning) xemacs: couldn't deduce a bold-italic version of the font
"Monospace-12".

Please specify X resources to make the bold-italic face
visually distinguishable from the default face.
For example, you could add one of the following to $HOME/Emacs:

XEmacs.bold-italic.attributeFont: -dt-*-medium-i-*
or
XEmacs.bold-italic.attributeForeground: hotpink
--8<---------------cut here---------------end--------------->8---